Download and Installation Problem with ADE

I have used ADE successfully for the past year for library downloads to my Nook.  I recently purchased a Nook Color, and was having trouble using ADE with it.  Someone suggested I uninstall ADE and re-install--I did uninstall; however, ADE will not allow me to re-install. 

At the ADE download page, I select "Launch" and receive this dialogue box:  "You may not have the necessary permission to use all the features of the program you are about to run.  You may run this program as a different user or continue to run program as current user."  I select "Current User" and receive the following dialogue box from ADE Setup:  "This installer requires administrative access" then "Unable to elevate to administrative rights, error 6"  As for the option to run the program as the "Administrator" it will not accept a password because I never created a password.

This happens on the computer I originally installed ADE (Windows Vista), as well as a Mac Laptop.  I can't find anything in this forum or thru internet searching that directly addresses this issue.  Please help!!!